1. Field of the Invention
The present invention relates to a sintered heat pipe, especially to a heat pipe having capillary grooves formed on an inner wall of a tube and a sintered layer of metal powder partially covering the capillary grooves.
2. Brief Description of the Prior Art
It is known that a heat pipe is a device having a high heat transfer capability. Liquid medium filled in the heat pipe is evaporated at a hot segment into vapor, and the vapor moves at a high speed along a vapor passage toward a cold segment. Then, the vapor is condensed into liquid medium at the cold segment. Due to capillarity the liquid medium returns to the hot segment through the wick structure. In this manner, heat can be transferred promptly from the hot segment to the cold segment.
U.S. Pat. No. 7,316,264B2 has mentioned a heat pipe having a plurality of capillary grooves longitudinally or axially formed on the inner wall of the tube member, as shown in its FIGS. 5 and 6. As the liquid medium in the capillary grooves is exposed to vapor and the flow direction of the liquid medium is opposite to that of the vapor, the vapor moving toward cold segment will blow the liquid medium in the capillary grooves toward the cold segment. This will disadvantageously hinders the return of the liquid medium back to the hot segment.
U.S. Pat. No. 7,316,264B2 further proposes to cover such capillary grooves with a sintered metal powder layer or a metal mesh. However, under the condition that the capillary grooves is completely covered, the sintered metal powder layer or the metal mesh hinders the entry of the liquid medium into the capillary grooves.